University of Minnesota study finds twice as many emperor penguins in Antarctica as expected

Using high-resolution satellite images, scientists have discovered that emperor penguins, whose Antarctic hardships were documented in the film "March of the Penguins," are twice as populous as previously thought.

The first-ever count of an entire animal population from space, conducted by University of Minnesota and British scientists, found that there are nearly 600,000 of the birds. The count provides a benchmark for monitoring the impact of environmental changes on the penguins.

"Now we know how many there are," said Michelle LaRue, a research fellow at the U's Polar Geospatial Center. "Going forward, we can determine how many there actually are and whether there needs to be some sort of conservation efforts."

Up until now it has been difficult to study the birds - they breed in remote areas of Antarctica that reach temperatures as low as -58 degrees Fahrenheit.

Scientists used a technique called pan-sharpening to increase the resolution of images from three different satellites. Using the improved images, a computer program distinguished the birds from the ice, their shadows and massive swaths of their brown penguin poop, called guano.

Peter Fretwell, geographer at the British Antarctic Society and lead author of the study - which will be published Friday, April 13 in the journal PLoS ONE - said the findings are groundbreaking for a number of reasons.

"We counted 595,000 birds, which is almost double the previous estimates of 270,000 to 350,000 birds," Fretwell said.

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"This is the first comprehensive census of a species taken from space."

Emperor penguins, the tallest and heaviest penguin species, are not considered threatened or endangered by the International Union for Conservation of Nature and Natural Resources. But scientists say climate change is a threat to the birds, which live and breed entirely on sea ice. Studies have predicted that the penguins could lose 87 percent of their population by the year 2100 due to the loss of sea ice and a diminishing food supply.

Emperor penguins on the sea ice close to Halley Research Station on Antarctica. (British Antarctic Survey)

"One of the colonies is already gone (from) the Dion Islands on the Antarctic Peninsula," LaRue said. "They need the sea ice for everything."

The study found seven previously undiscovered colonies of emperor penguins.

Emperor penguins are ideal for a satellite census, LaRue said, because they are relatively immobile for months at a time, especially during breeding season.

Other species might also be candidates for a satellite census, LaRue said. Walruses in Alaska, for instance, come back to the same location at certain times of the year.

Weddell seals, also endemic to Antarctica, don't move much, either.

LaRue said the penguins are fascinating not just because of their documentary-film fame.

"They exude their name," she said. "They're a very stately and calm animal."

When she and other scientists visited Antarctica to see emperor penguins in person, she said the birds were gentle and curious, exploring humans who were careful not to make any sudden moves on the ice.

"They're just really cool creatures," LaRue said. "They'll get one to two feet away and just kind of check you out. They're not aggressive at all."